Papermaking drier drum



1964 H. E. MALMSTROM ETAL 3,

PAPERMAKING DRIER DRUM 5 Sheets-Sheet l Filed April 15, 1959 37 Jan. 21,1964 H. E. MALMSTROM EI'AL 3, 3

PAPERMAKING DRIER DRUM I Filed April 15, 1959 5 Sheets- -Sheet 2 Jan.21, 1964 H. E. MALMSTROM EI'AL. 3, ,743

PAPERMAKING DRIER DRUM 5 Sheets-Sheet 3 Filed April 15, 1959 @W 7/ m M,

1964 H. E. MALMSTROM ETAL 3, ,743

PAPERMAKING DRIER DRUM Filed April 15, 1959 5 Sheets-Sheet 4 \D a N 40as pun/v0! ma 1; Of 0012 United States Patent 3,113,743 PAPERMAKING DRERDRUM Homer E. Maiznstrom, Appieton, and Keith C. Mart ny, Neenah, Wisassignors to Kimberly-Clark Corporation, Neenah, Wis, a corporation ofDelaware Filed Apr. 15, 1959, Ser. No. 806,475 5 lainis. (Cl. 34-11(5)The invention relates to pressure vessels and more particularly to drierdrums for use in the manufacture of paper and to methods of forming thedrums.

A papermaking machine of the usual type comprises one or more drierdrums which are heated by steam pressure and over which the wet paperweb travels after being couched from the forming wire of the papermachine and partially dewatered between felts, being pressed onto thesurface of the drums and dried to a desired final moisture content. Themore usual paper machines contain a large number of small drier drumsbetween which the paper is transferred while the so called Yankee typepaper machine utilizes a single large drier drum on which the wet paperweb is dried within a single revolution.

The Yankee drier drums are cast or welded structures and are ofconsiderable size, having a diameter of 8 to 15 feet and a length of 10to feet, Weighing in the neighborhood of 65 or 70 tons. Duringoperation, the drier drums are subjected to both internal and externalpressures. A pressure roll bears against the external surface of thedrier drum at the point where the wet paper sheet is first applied tothe drier drum, and the pressure roll exerts a force of from 200 poundsto 450 pounds per lineal inch across the entire face length of thedrier. Due to this great pressure, the pressure roll deflects; and it istherefore necessary to crown the pressure roll slightly so as tomaintain an even pressure across the entire face length of the pressureroll. Due to this bending, the circumferential speed at the center ofthe pressure roll is greater than at the sides and tends to cause thefelt passing between the pressure roll and drier drum to wrinkle out offlat condition, causing uneven wear of the felt. In order to overcomethis wear condition, the drier drum is also crowned; and, theoretically,the pressure roll and drier drum are preferably crowned in proportion totheir diameters. Practically, the crowning that may be applied to thedrier drum is limited, however, due to the fact that a doctor bladerides in contact with the drier drum for the purpose of creping oi thepaper, when dried, from the drier drum.

In order to heat the drier drum so that it effectively dries the paperweb, steam is introduced at rather high pressure, such as 40 to 60pounds per square inch, for example, within the drier drum and providesan internal pressure in the drum.

It has been found that, although a conventional drier drum exhibits aproper crowning at the temperature at which it is used, such as at 287F., at 40 pounds per square inch steam pressure, for example, when a wetpaper web is applied onto the drier drum, the drum loses its optimumcrowning and has high points at its ends, due to the fact that the wetpaper Web maintains the surface ofvthe drum covered by the web at alower temperature than the temperature of the steam supplied to the drumwhile the edges of the drum progressively increase in temperature towardthe drum ends. Due to the existence of these high points, the doctorblade scraping the dried paper web from the drier drum causes excessivewear of the drum at its ends.

Yankee drier drums are generally made of cast iron, and exhibit wear toa noticeable extent at the ends of the drum due to the scraping actionof the doctor blade, so

"ice

that the drums must be reground after 9 months or one year of usage.Yankee drier drums may also be made of other better heat conductingmaterials, such as aluminum-bronze alloys, and such drier drums wear toa greater extent, due to the fact that, although such alloys conductheat better than cast iron and are thus more suitable in this respect,they are softer and thus wear easier under doctor blade action. Also,such alloys have a greater coefficient of thermal expansion than castiron, and drums of such alloys thus become more out of shape than docast iron drums and wear more for this reason also.

This wearing action of the doctor blade on the ends of the drum surfaceis still more pronounced when the drum surface is made from sheets ofaluminum bronze alloy welded together in a manner such as is described,for example, in a co-pending application of C. G. R. Johnson, Serial No.699,704, filed November 29, 1957, now Patent 3,052,039, issued September4, 1962. With such a construction, the drum has been found to wear inparticular just behind the welds joining the plates together, adjacentthe side edges of the drum.

It is an object of the present invention to provide an improved drierdrum having a crowned outer surface presenting no ridges adjacent theedges of the drum subject to undue wear by the doctor blade, under theconditions of usage of the drum, namely, when steam is applied to thedrum for heating it and a wet paper web extends around the drum withinshort distances of the drum ends for drying the web.

It is another object of the invention to provide an improved drier drumof this type which, when an uniform temperature, is gradually crownedalong most of its length and is more severely crowned or taperedadjacent the ends of the drum, with the drum being at uniformtemperature, so that when the drum has a web of wet paper applied to itand steam is supplied to it, the drum exhibits a proper crowning, nearlyin a straight line from each end to the middle of the drum.

It is a more specific object of the invention to provide such animproved crowning outline on a drum made from a material that is betterheat conducting but softer than cast iron, such as aluminum-bronzepreviously mentioned, particularly in which the drum is made up of aplurality of sheets of this material welded together.

It is also an object of the invention to provide improved methods forforming drums having the outline previously referred to, having no endridges subject to undue wear by the doctor blade under operatingconditions of the drum.

The invention consists of the novel constructions, ar-

rangemen-ts, devices and methods to be hereinafter described and claimedfor carrying out the above stated objects and such other objects, aswill be apparent from the following description of a preferred form ofthe invention and methods for making the same, illustrated withreference to the accompanying drawings, wherein:

P16. 1 is fragmentary side elevational view of a paper machineincorporating a drier drum embodying the principles of the invention;

FIG. 2 is a fragmentary end View on an enlarged scale of the drier dnumshown in FIG. 1;

FIG. 3 is a longitudinal sectional view on a reduced scale of the drierdrum;

FIG. 4 is a perspective view of the outer cylindrical shell of the drierdrum;

FIG. 5 is a graphical illustration of the contour of the external drumsurface of a conventional drier under two different conditions;

FIG. 6 is an illustration similar to FIG. 5 but of the improved drierdrum contour of the present invention;

FIG. 7 is a side elevational view of the drier drum on 30 in shaftsection 2i! to the exterior.

a reduced scale showing a plurality of water showers applied to the drumfor reducing the external temperature thereof in grinding the externaldrum surface; and

FIG. 8 is a view similar to FIG. 7 showing a cooling fabric applied tothe drum during the grinding operation.

Like characters of reference designate like parts in the several views.

Referring now to the drawings, the Yankee type paper machine illustratedcomprises a supporting frame 16 which rests on a suitable foundation 1.1and rotatably supports a drier drum 12. The drier drum includes agenerally cylindrical shell 13 having end flanges 14 which are bolted toheads 15. The heads 15 enclose the ends of the shell and are providedwith aligned axial openings which receive a hollow shaft 16. The drierdrum is mounted for rotation by providing the ends of the shaft 16 withjournals 17 which are rotatably secured in bearings 18 secured to theframe 10.

The shaft 16 is formed of two hollow axially aligned sections 19 and243' which are separated by a separator plate 21. The separator 21 isprovided with a thickened rim 22, and a series of openings 23v extendthrough the rim and communicate with the interior of the shell 13. Steamnozzles 24 are threaded into the openings 23 and serve to distributesteam from the interior 25 of the shaft section 19 to the interior ofthe shell 13. A pair of scoops 26 are secured to the ends of pipes 27which extend radially through openings 28 in the shaft section 2%. Theinner ends of the pipes 27 are connected to a conduit 29 which extendsoutwardly through the passage The scoops 26 serve to scoop out the steamcondensate from the interlor of the shell :13 and discharge the samethrough the conduit 2? to the exterior.

The drier drum .12 is rotated by a conventional drive mechanism, notshown, which is attached to the end of the shaft 16 by a suitable gearor pulley arrangement.

A heating hood 31 is secured to the frame 10 and extends around theupper portion of the dnum 12. Hot air inlets 31a and suitable outlets(not shown) are provided in the hood for the entry and the discharge ofthe air or other heating medium applied to the hood.

The wet paper web to be dried is carried by a felt web 32 which travelsaround felt rolls 33. The paper web is forced against the surface of thedrier shell 13 by a pressure roller 34 which is rotatably mounted inbrackets 35 secured to an arm 36. The arm 36 is pivoted at 37 to theframe 16, and the pressure roller 34 is forced against the surface ofthe drier shell 13 by a ram 38 of a hydraulic cylinder 39 which bearsagainst the arm. 36.

The dried paper web is removed from the. surface of the drier shell by acreping doctor, which includes a doctor blade 40 removably securedwithin a doctor blade holder 41. The ends of the holder 41 are providedwith shafts 42 which are rotatably mounted within guide blocks 43. Theblocks '43, in turn, are each slidably mounted within a slide assembly44 attached to pivot frame 45 pivotally carried by the frame 10. Throughthe slide arrangement provided by the guide blocks 43 and the slideassembly 44, the vertical position of the doctor blade 40 can be varied,as desired, to obtain the best creping angle.

The doctor blade holder 41 and the blade 40 are pivoted by a togglemechanism 46 which is attached through a lever arm 47 to one of theshafts 42. In addition, a spring loading mechanism 48 is connectedthrough the toggle mechanism 46 to provide a resilient contact for thedoctor blade against the surface of the drier shell 113.

In addition to the vertical and pivotal adjustment for the doctor blade40, the doctor blade is adapted to oscillate in a direction generallyparallel to the axis of the shell 13. The oscillating motion is providedby an cecentric drive shown generally at 49, which is connected to oneof the shafts 42. The oscillating motion is permitted by a loose fitbetween the pivot frame 45 and the frame 19 and permits the doctor bladeto move back and forth across the shell surface as the shell 13 rotates,to prevent uneven wear of the doctor blade and of the drier drum duringoperation.

The shell 13 may be a single casting, as of cast iron, if desired, andin this case the other parts of the drum 12, such as the heads 15 andshaft 16 are likewise made of cast iron, in order to assure that thecomplete drum has the same coefiicient of thermal-expansion. As analternative, the shell 13 may be formed of a plurality of plates 50which are welded together along their edges, at 51 and 52, as seen inFIG. 4. This construction is particularly suitable if an alloy having ahigh heat conductivity, as compared to cast iron, is used, such as analuminumbronze alloy, having, for example, up to 8 percent of aluminum,up to 4 percent of iron, up to 5 percent of nickel, up to 5 percent ofmanganese, up to 2 percent of tin, up to 5 percent of zinc, and thebalance being copper, such as is, for example, disclosed in thecopending application of John F. Klement, Serial No. 682,577, filedSeptember 9, 1957, now Patent 2,937,965, issued May 24, 1960. In thiscase, the other parts of the drum are likewise formed of the samematerial, and the welds would be made with substantially the samematerial also, to assure that the drum as a whole has the same thermalcoeflicient of expansion.

In operation, the drum 12 is driven from any suitable power source; andthe pressure roller 25, rotatably mounted on the brackets 35, rotates,with the felt 32 and the wet paper web 53 carried on the under surfaceof the felt passing between the roller 34 and the drum 12. The paperweb, after passing between the nip of the roller 34 and drum 12, passeson to the drum 12 and is dried during rotation of the drum 12 by thetime the paper reaches the creping doctor blade 40. The blade 40 crepesthe paper from the drier drum 12, and the paper is wound on any suitablerolls (not shown).

The pressure roll 34 and the drier drum 12 have customarily been crownedfor reasons which have been hereinbefore mentioned. Assuming that thedrier drum 12 is operated at 40 pounds per square inch steam pressure,for example, the crowning of the drier drum has been approximately inthe form shown by curve A in FIG. 5, 7

this being in the form of the drum without a web of paper on the drumand at the operating steam pressure. Under these conditions, it will beunderstood that the temperature throughout the drier drum is uniform. Ithas been found that when a wet paper sheet is applied on to the drierdrum when the drum is in use, the drum is distorted so that the drum hasan exterior surface substantially in the form shown by curve B of FIG.5. It will be noted that the drum surface as a whole has decreased indiameter and that the drum surface increases in diameter from a lowpoint 54 to a high point 55, with the point 55 being substantially atthe edge 56 of the paper web 53 extending around and being dried by thedrum. The contour curves A and B, as well as the curves C and D in FIG.6, to be subsequently referred to, with reference to the particularvalues of ordinates and abscissae shown, are for a particular drier drummade from the aluminumbronze alloy, and are illustrative only of oneexample of drier drum.

Due to the existence of the high point 55 on each edge of the drierdrum, it has been found that the doctor blade 40 causes a substantiallygreater amount of wear at the ends of the drum 12 than in the centerportion of the drum. If the drum 12 is made completely out of the castiron, the increased wear of the drum at the ends as contrasted to thecenter portion of the drum necessitates a regrinding of the drum,generally speaking, for every six months or nine months of usage. In theevent a softer material, such as an aluminum-bronze alloy, as previouslymentioned, isused for the shell 13, the wear is noticeable much sooner,and assuming the shell 13 is made from a plurality of sheets of thismaterial welded together as shown in FIG. 4, the wearing action isparticularly noticeable in areas 57 (see FIG. 2) adjacent to and lyingjust behind the welds 52 and adjacent the edges 56 of the paper web 53.The formation of such unduly worn areas 57 necessitates the regrindingof the softer drum after much shorter periods of usage.

The present invention contemplates the provision of an outer shellsurface on the drum 12 which does not include the high points 55adjacent the edges but rather a surface which gradually increases indiameter to the drum center from the drum edges, this contour to existunder actual operating conditions, with the operating steam pressure(such as 40 pounds per square inch) applied within the drum and with theWeb of wet paper travelling around the drum. The shape of the shell maybe in the form shown by curve C in FIG. 6, for example. Preferably theshape of this curve, from the edge of the paper web at 56 to the centerof the drum, is of cosine form. For a particular drum, the equation forthe curve C is as follows:

.030 .Olo [cos L /1 1] The constants of this equation would of course bedifferent with different dimensions and coefiicients of thermalexpansionof different materials used. The term is in degrees. The constant .030is the measurement in inches of the reduction of diameter at the centerof the drum 12 that occurs when the sheet is applied. Both Y and X aremeasured in inches from an origin 58. The X term is the distance ininches from the center of the drum measured until the point 56 at theedge of the paper web is reached, and the term L is the length of theface of the drier in inches measured to the point 56, the width of thesheet being 128 inches for example. As will be observed from theequation, the cosine term, when X is zero, equals unity, so that thepart of the equation in brackets is zero, whereby the reduction indiameter of the drum at its center of .030 inch is indicated. From thepaper edges 56 to the adjacent edges of the drum, the drum is dubbed orreduced in diameter more sharply than curve C, since this is outside thepaper drying area.

The drier drum 12 may be ground into the form indicated by curve C ofFIG. 6 by using conventional grinding mechanism, such as that shown inthe patent to R. G. Minarik et al., No. 2,579,391, issued December 18,1951. The grinding equipment may be used on the drum 12 when the papermachine is in actual operation, if desired, such as shown in FIG. 1. Thegrinding equipment may comprise rolls 5?, 6t) and 61, all or which aredisposed and rotatably supported between opposite parts of thesupporting frame it An abrasive belt 62 is provided over the rolls 59,6d and 61, and the rolls and belt are so positioned between the doctorblade 4% and the pressure roll 34 that the abrasive belt 62 grinds thesurface of the drum 12 when the paper machine is in operation. The belt62 may be driven and may be guided so as to form the curve C on theexterior surface of the drum 12 by the mechanism shown in the R. G.lvlinarik patent. The web of paper passing around the drum 12, underthese conditions, maintains the exterior surface of the drum between thepoints 56 below the temperature of the steam pressure supplied to thedrum. For a particular aluminum-bronze drum 12, and for a 40 pounds persquare inch steam operating pressure, the exterior surface of the drumbetween the points 56 is maintained by the wet paper web at about 260degrees; the temperature inside the drum is 287 degrees; and the averagetemperature of the shell 13 is 243 degrees.

The cosine curve C may also be ground on the drum the diameter as seenin curve D in this range.

under simulated operating conditions as shown in FIG. 7 by directing aplurality of water sprays 63 onto the surface of the drum between thepoints 56 so as to maintain the outside temperature of the drum at theoperating temperature with the wet paper web applied to it, which in theabove mentioned case is 200 degrees. With the sprays of water thusdirected on the drum, the drum is ground in a conventional manner, suchas with the rolls 59, 60 and 61 and abrasive belt 62 to have the desiredcontour.

The drum may also be ground when it is at a uniform temperature such asthe temperature corresponding to the operating steam pressure of 40pounds per square inch. At this time it is not cooled on its externalsurface by means of the water sprays or wet paper web. Since the outeredge portions of the drum can be expected to be too high, the edgeportions are ground down to a smaller diameter than would be expectedfrom the curve C. In particular, the drum may be ground under theseconditions to have a surface as shown by the curve D as seen in FIG. 6which has been found to result in the surface contour C when the drum isused under actual operating conditions with the paper web passing overand being dried by the drum. For the particular drum hereinbeforementioned, the equation for the curve D from the origi 53 to the edge 56of the wet paper web that would be applied to the drum, is as follows:

(a) {.015 [cos The drier drum 12 may also be ground at room tem peratureinto proper shape, so that it has the ultimate shape as shown by curve Cunder operating conditions, The proper contour of the drum 12 at roomtemperature is much like the curve D and is defined by an equation suchas that for Y given above, except that the con stants are different.

With respect to the relative importance of the various terms of thevalue for Y given above, it may be stated that the term a is relativelythe most important in the middle part of the drum, that is, fromapproximately 20 inches inwardly from each end of the drum toward themiddle. This is the same as the value or Y given above except for aconstant (.030 for the particular drum considered) indicating thereduction in diameter at the drum cent r under Web drying conditions.The second term [7 of the equation for Y becomes the most important termbetween 6 inches and 20 inches inwardly from each end of the drum whichis reflected by the sharp drop olf of Between zero and 6 inches inwardlyfrom each end of the drum, the drum is dubbed to further decrease thelikelihood of doctor blade wear at the extreme ends of the drum 12.

The drum may also be ground to the desired surface contour under othersimulated operating conditions, such as shown in FIG. 8. In this case astrip or puttee as of a relatively open mesh cloth, similar to cheesecloth, is wound around the drum 12 within about 20 inches of the edgesof the drum. The middle portion of the drum covered by the cloth striphas been previously ground into conventional shape as shown by the curveA of FIG. 5, which approximates curve D from the center of the drum towithin 20 inches of each edge. Water showers 63 are then sprayed ontothe cloth strip 64, so that the cloth maintains the external surface ofthe drum toward the edges of the drum in the vicinity of the 200 degreesoperating temperature previously mentioned. The edge portions of thedrum, not covered by the cloth strips 64, are then ground, using forexample the rolls 59, 6t) and 61 and abrasive belt 62, so as to have thecontour shown by curve C of FIG. 6 in this range. As is apparent fromthe above discussion of curves C and D, for the particular drum underconsideration, the curve D under operating steam pressure approximatelyresults in the curve C when the paper web is applied from the middle ofthe drum to Within about 20 inches of the drum ends, per initting thegrinding under these simulated operating conditions to give anapproximately correct contour.

Regardless of which method is utilized for forming the external surfaceon the drum as shown by the curve C, the reduction in diameter at thedrum ends, particularly in the region of the web edges 56,advantageously causes a reduction in wear in the vicinity of thesepoints on the drum. This is particularly true if the drum is made of ahigh heat conducting material, such as the aluminum bronze alloymentioned above, which is relatively soft and has a higher coefiicientof thermal-expansion than cast iron. If the shell 13 is made of sheetswelded together, the drum contour of the invention results in lessenedwear in the regions 57 of the drum surface. The contours C and D alsoprovide a more even pressure on the drum surface from the pressure roll34 resulting in more even wear of the felt 32.

it is to be understood that the invention is not to be limited to thespecific constructions, arrangements and methods shown and described,except only insofar as the claims may be so limited, as it will beunderstood to those skilled in the art that changes may be made withoutdeparting from the principles of the invention.

What is claimed is:

1. A drier drum adapted to have a heated fiuid under pressure suppliedto it for heating the drum for drying a web or" sheet material on thedrum periphery and comprising a generally cylindrical drier shell forreceiving the web; said shell under the pressure of said heated fiuiddecreasing in diameter from the center of the shell to the shell endswith the profile of the shell in a relatively long central zone, whichextends for the major portion of the length of the shell, being arelatively gradual curve and the profile of the shell in substantiallyshorter intermediate zones on the ends of said central zone, whichextend for minor portions of the length of the shell, being curves whichare substantially sharper than the curve defining the profile of saidcentral zone and the shell in still shorter end zones decreasing indiameter substantially more abruptly toward the shell ends than in saidintermediate and central zones.

2. A drier drum adapted to have steam under pressure supplied to it fordrying on its periphery a Web of sheet material having a width of apredetermined dimension and the drum comprising a generally cylindricaldrier shell and heads for enclosing the ends of the shell and supportingthe shell; said shell under steam pressure decreasing in diameter fromthe center of the shell to the shell ends with the profile of the shellin a relatively long central zone, which is within said dimension andextends for the major portion of the length of the shell, being arelatively gradual curve and the profile of the shell in shorterintermediate zones on the ends of said central zone, which with saidcentral zone complete said dimension and extend for minor portions ofthe length of the shell, being curves that are substantially sharperthan the curve defining the profile of said central zone and the shellin still shorter end zones outside of said dimension decreasing indiameter substantially more abruptly toward the shell ends than in saidintermediate and central zones.

3. A drier drum adapted to have steam under pressure supplied to it fordrying at web of sheet material on the drum periphery and comprising agenerally cylindrical drier shell and heads for enclosing the ends ofthe shell and supporting the shell, said shell under steam pressuredecreasing in diameter from the center of the shell to the shell withthe profile of the shell in a relatively long central zone being arelatively gradual curve and the profile of the shell in shorterintermediate zones on the ends of said central Zone being curves thatare substantially sharper than the curve defining the profile of saidcentral zone and the shell in still shorter end zones decreasing indiameter substantially more abruptly toward the shell ends than in saidintermediate and central zones; said intermediate zones encompassingminor portions of the length of the shell and said central zoneencompassing the major portion or" the length of the shell that isseveral times longer than the lengths of said intermediate zones takentogether.

4. A drier drum adapted to have steam under pressure supplied to it fordrying on its periphery a web of sheet material having a width of apredetermined dimension and the drum comprising a generally cylindricaldrier shell and heads for enclosing the ends of the shell and supportingthe shell; said shell under steam pressure decreasing in diameter fromthe center of the shell to the shell ends with the profile of the shellin a relatively long central zone, which is within said dimension andextends for the major part of the length of the shell to about 20 inchesfrom the ends of the shelhbeing a relatively gradual curve and theprofile of the shell in shorter intermediate zones on the ends of saidcentral zone, which with said central zone complete said dimension andextend for minor portions of the length of the shell, being curves thatare substantially sharper than the curve defining the profile of saidcentral zone and the shell in still shorter end zones outside of saiddimension decreasing in diameter substantially more abruptly toward theshell ends than in said intermediate and central zones; the length ofthe shell encompassed by said central zone being several times thelength of the shell encompassed by said two intermediate zones takentogether.

5. A drier drum adapted to have steam under pressure supplied to it fordrying a web of sheet material on the drum periphery and comprising agene ally cylindrical drier shell of an aluminum bronze alloy and headsfor enclosing the ends of the shell and supporting the shell; said shellunder steam pressure of approximately 40 pounds per square inchdecreasing in diameter from the center of the shell to the shell endswith the profile of the shell in a relatively long central zone, whichextends for the major portion of the length of the shell, being arelatively gradual curve and the profile of the shell in shorterintermediate zones on the ends or" said central zone, which extendforminor portions of the length of the shell, being curves that aresubstantially sharper than the curve defining the profile of saidcentral zone and the shell in still shorter end zones decreasing indiameter substantially more abruptly toward the shell ends than in saidintermediate and central zones; said end zones extending from the endsof said shell and encompassing about six inches of the shell length andsaid central zone extending to approximately 20 inches from the ends ofthe shell and encompassing a length of the shell which is several timesthe length of the shell encompassed by said intermediate zones takentogether.

References ited in the file of this patent UNITED STATES PATENTS 243,615Piper June 28, 1881 1,718,977 Overton July 2, 1929 1,779,467 EinsteinOct. 28, 1930 2,033,324 Caster et al Mar. 10, 1936 2,519,105 Blue Aug.15, 1950 2,779,104 Sims Ian. 29, 1957 2,817,908 Hornboster new??? Dec.31, 1.957

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noe 1x 118743 January 21 1964 Homer Ea Malmstrom et al@ It is hereby certifiedthat error a ppears in the above numbered patent requiring correctionand that the sa id Letters Patent should read as corrected below.

Column 2, line 31 for "an" read me at =5 column 4,, line 46 strike out"in; column 6 line 48 for "or" read for Signed and sealed this 16th dayof June 1964,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A DRIER DRUM ADAPTED TO HAVE A HEATED FLUID UNDER PRESSURE SUPPLIEDTO IT FOR HEATING THE DRUM FOR DRYING A WEB OF SHEET MATERIAL ON THEDRUM PERIPHERY AND COMPRISING A GENERALLY CYLINDRICAL DRIER SHELL FORRECEIVING THE WEB; SAID SHELL UNDER THE PRESSURE OF SAID HEATED FLUIDDECREASING IN DIAMETER FROM THE CENTER OF THE SHELL TO THE SHELL ENDSWITH THE PROFILE OF THE SHELL IN A RELATIVELY LONG CENTRAL ZONE, WHICHEXTENDS FOR THE MAJOR PORTION OF THE LENGTH OF THE SHELL, BEING ARELATIVELY GRADUAL CURVE AND THE PROFILE OF THE SHELL IN SUBSTANTIALLYSHORTER INTERMEDIATE ZONES ON THE ENDS OF SAID CENTRAL ZONE, WHICHEXTEND FOR MINOR PORTIONS OF THE LENGTH OF THE SHELL, BEING CURVES WHICHARE SUBSTANTIALLY SHARPER THAN THE CURVE DEFINING THE PROFILE OF SAIDCENTRAL ZONE AND THE SHELL IN STILL SHORTER END ZONES DECREASING INDIAMETER SUBSTANTIALLY MORE ABRUPTLY TOWARD THE SHELL ENDS THAN IN SAIDINTERMEDIATE AND CENTRAL ZONES.